It might not be immediately obvious, but with every solar panel installed comes a simple but essential piece of maintenance: regular cleaning.

Just like the windows on your house, the glass on the top of solar panels gets coated with dust and dirt that cuts down the amount of light that passes through. More so than windows, solar panels are particularly vulnerable because they often lie at a shallow angle in an exposed location.

A thin layer of dust and grime can reduce efficiency by around 15 percent—that’s a lot of potential power to waste just because the glass isn’t kept clean.

So Japan’s Sharp, a leading manufacturer of solar panels and generation systems, has come up with a robotic answer to this problem. The company has developed an automatic cleaner that will latch on to the top of a bank of solar panels and clean them one by one.

The device, which is on show at this week’s Ceatec expo in Tokyo, can clean about 1,800 panels per hour. It requires a two-person team to operate and will cover around 5,220 panels before its battery runs dead, the company said.

Martyn Williams

In contrast, current manual cleaning requires a 10-person team that can get through about 7,380 panels per day, so the automatic cleaner is much more efficient.

Sharp has already conducted trials of the cleaner at Thailand’s Changwat Lop Buri. The plant is one of the largest solar generation facilities in the world, covering an area of 2 kilometers by 1 kilometer, and contains 640,000 solar panels to produce up to 73 megawatts of electricity.

By hand, cleaning all those panels was a three-week job that required 62 workers. Using the solar cleaner, the job was accomplished in the same amount of time using about 20 workers, Sharp said.

In addition to requiring fewer workers, it also consumes just one-tenth the amount of water of the manual cleaning process—about 0.3 liters per panel.

Sharp is working toward commercializing the cleaner, which will first work on the company’s own panels. Adapting it to clean solar panels made by different companies shouldn’t be difficult, and Sharp will consider that after initial commercialization, said Akimasa Umemoto, a department general manager at Sharp’s Solar Systems Group.

Sharp is already working on a next-generation system that doesn’t require water. While the current prototype is suitable for use in Southeast Asian countries and places such as the U.S., the waterless version will be aimed at the Middle East, where access to large amounts of water can be problematic.

Updated at 10:20 a.m. PT with a video report from IDG News Service.

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